An example of frame configuration along the time axis in a conventional radio communication system is shown in FIG. 1. In FIG. 1, reference code 1 indicates data symbols, reference code 2 pilot symbols, and reference code 3 a unique word. In order to demodulate a signal transmitted from a transmitting apparatus, a receiving apparatus must acquire time synchronization with the transmitting apparatus. For this purpose, the receiving apparatus acquires time synchronization by detecting unique word 3, for example. Also, when demodulating data symbols 1, the receiving apparatus compensates for channel fluctuations using pilot symbols 2.
However, in a conventional radio communication system, since a unique word and pilot symbols that carry no information are inserted on the time axis of the frame configuration, the data transmission speed falls proportionally.
Thus, the idea has been considered of using a different frequency band for unique words and pilot symbols from that used for data, and transmitting these at the same time as data. However, a drawback in this case is that the frequency band used becomes wider. There is also a drawback in that, since a different frequency band from that for data is used, unique words and pilot symbols undergo different propagation path fluctuations than data, and precision when compensating for channel fluctuations degrades.